In the process of producing strip and plate in a rolling mill the temperature of the rolled material is a very important consideration from a gauge, physical and quality standpoint, the latter including uniformity, shape and flatness. One aspect of material temperature has to do with the temperature rundown in the material (bar) rolled in the hot mill, whether in a reversing mill, semi-continuous, or continuous mills. Because the trailing end portion of the hot bar is normally subject to considerable greater heat losses while it waits to be rolled and while it is exposed to the atmosphere compared with the earlier portion to be rolled, the bar has a temperature gradient decreasing from the leading end to the trailing end. While this gradient is generally linear, certain portions of the affected area are not. This temperature gradient develops a progressively greater roll force for a given desired rolled gauge. In order to attempt to compensate for this condition many and varied corrective procedures have been put in practice and/or suggested.
These attempts has sought both to treat the bar before it is finally rolled, for example, in a reversing hot mill or during the rolling of the bar as in the finishing train of a continuous hot mill. Examples of the former are delay tables, coil boxes and temperature control devices which are employed to equalize or reduce the temperature gradient before the final rolling pass. Examples of the latter are mill gauge control, mill speed control and mill temperature control systems such as interstand cooling.
None of the prior art systems when used singly or in combination with one or more of the other systems have been totally successful. Moreover, some of the more successful ones represent a considerable outlay in capital investment and operational expense and maintenance.